在VB.NET中禁用文本框时遇到问题

如何第二次禁用文本框? 这是我的代码,在表单加载中,文本框被禁用,除非用户将输入数据库中的ID号。但是,如果用户输入数据库中的一个ID号,然后再次输入另一个不存在的ID号, 这就是这个代码的由来,但它有问题,它不会在鼠标单击时禁用文本框,这是什么正确的方法?

Private Sub Button12_MouseClick(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles Button12.MouseClick
        Dim NoAcc As String
        Dim NoAccmod2 As String
        Dim NoPas As String

        Dim sqlcon As New MySqlConnection("Server=localhost; Database=school;Uid=root;Pwd=nitoryolai123$%^;")
        Dim sqlcom As MySqlCommand = New MySqlCommand("Select * from student where IDNO= '" & TextBox14.Text & "' ", sqlcon)

        sqlcon.Open()

        Dim rdr As MySqlDataReader
        rdr = sqlcom.ExecuteReader

        If rdr.HasRows Then
            rdr.Read()
            NoAcc = rdr("IDNO")
            If (TextBox14.Text <> NoAcc) Then
                MsgBox("ID Number is not yet registered!, please register first in the general information before trying to register parents information", MsgBoxStyle.Information)
                TextBox7.Enabled = False
                TextBox8.Enabled = False
                TextBox9.Enabled = False
                TextBox10.Enabled = False
                TextBox11.Enabled = False
                TextBox12.Enabled = False
                TextBox13.Enabled = False
            End If
        End If